1. Field of the Invention
The present invention relates to a condenser structure with a liquid tank, which is used with a vapor compressing type refrigerator for car air conditioners. The condenser is connected in series between a compressor and an evaporator, and condenses refrigerant to radiate heat from the refrigerant, removes the water content and foreign materials from the refrigerant, and then feeds the clean refrigerant to the evaporator.
2. Description of the Related Art
A refrigerator of the vapor compressing type is incorporated into a car air conditioner for controlling temperature in a car room and dehumidifying air in the car room. This type of the refrigerator is disclosed in Japanese Patent Publication No. Hei. 4-95522. A circuit diagram showing the basic construction of the refrigerator is shown in FIG. 23. In the figure, gaseous refrigerant at high temperature and high pressure is discharged from a compressor 1 and passes through a condenser 2. When passing through the condenser, a heat exchange between the refrigerant and air is performed, so that the refrigerant is decreased in temperature, condensed and liquidized. The resultant liquid refrigerant is temporarily stored in a liquid tank 3, and then fed to an evaporator 5 through an expansion valve 4. In the evaporator 5, the liquid refrigerant is evaporated. In the process of evaporating the refrigerant, the evaporator temperature decreases as the result of absorbing the latent heat. Accordingly, if air to be air conditioned is applied to the evaporator 5, temperature of the air decreases and the air is dehumidified. The refrigerant evaporated in the evaporator 5 is sucked by the compressor 1. Then, the refrigerating cycle is repeated.
In the vapor compressing type refrigerator for car air conditioners, the liquid tank 3 is manufactured separately from the condenser 2, and placed in the middle of the pipe which connects the condenser 2 to the evaporator 5. In the case of the refrigerator in which the condenser 2 and the liquid tank 3 are separately provided, a large space is required for installing the liquid tank 3 therein, and vibration-proof measures must be taken for the condenser 2 and the liquid tank 3, respectively.
To solve those problems, there are many proposals as disclosed in Japanese Patent Publication Nos. Hei. 3-87572, 4-103973, 4-131667, and the like. The proposal disclosed in Japanese Patent Publication No. Hei. 4-103973 is schematically shown in FIG. 24. As shown, a condenser 2 includes a couple of header pipes 6a and 6b which are extend vertically (when viewed also in FIG. 24) and spaced horizontally (when viewed in FIG. 24). A plural number of flat heat transferring pipes 7 are disposed between the couple of the header pipes 6a and 6b. These flat heat transferring pipes 7 are horizontally extended and vertically spaced. Both ends of the heat transferring pipes 7 are air- and liquid-tightly coupled with the header pipes 6a and 6b so that the inner flow passages of the flat heat transferring pipes 7 communicate with the inner sides of the header pipes 6a and 6b, respectively. Corrugated fins 8 formed of zig-zagged thin metal plate are located between the adjacent flat heat transferring pipes 7, to thereby form a core section 9. Side plates 10 and 11 are provided on the upper and lower sides of the core section 9, respectively. The both end portions of the side plates 10 and 11 are fastened to the inner sides of the upper and the lower ends of the header pipes 6a and 6b, respectively.
In the thus constructed condenser 2, the core section 9 effects heat exchange between the refrigerant flowing through the flat heat transferring pipes 7 and air flowing along the flat heat transferring pipes 7, and condenses and liquidizes the refrigerant. Gaseous refrigerant is fed into an inlet pipe 12, which is provided at the top of the header pipe 6a (located on the right side in FIG. 24). The refrigerant flows between the header pipe 6a and the header pipe 6b (located on the left side in FIG. 24) in going/returning manner, through the flat heat transferring pipes 7 of the core section 9. During this flow of the gaseous refrigerant, the refrigerant is condensed and liquidized. The resultant liquid refrigerant is gathered in the lower end of the header pipe 6a, and fed through a refrigerant transporting pipe 13 to the liquid tank 3.
The liquid tank 3 is fastened onto the outer surface of the header pipe 6a. Specifically, a cylindrical case 14, which defines the liquid tank 3, is fastened to the side wall of the header pipe 6a by means of hard soldering or brazing. An opening of the bottom of the case 14 is closed with a bottom plate 15, while an opening of the top of the case 14, with a top plate 16. The refrigerant transporting pipe 13 is inserted through the bottom plate 15 into the case 14 so as to extend passing through the axis of the center of the case. A cylindrical space 18 is formed between the outer surface of the refrigerant transporting pipe 13 and the inner surface of the case 14. A number of small holes 17 are perforated in the upper portion of the refrigerant transporting pipe 13 that is located in the upper portion of the case 14. Liquid refrigerant, which was fed from the header pipe 6a to the refrigerant transporting pipe 13, may flow out through the small holes of the refrigerant transporting pipe 13. In the mid portion of the cylindrical space 18, a filter 19, a drying agent 20 and a porous holder plate 21 are stacked in this order when counted from the lower side. The filter 19 is made of porous material, such as felt, and has a function to filter foreign materials, for example, dust. The drying agent 20 is made of silica gel, calcium chloride, or the like. The porous holder plate 21 is formed with a wire net, punching metal, or the like. An outlet pipe 22 is provided at the lower end of the case 14. The liquid refrigerant, which is gathered in the lower end of the cylindrical space 18, flow out through the outlet pipe 22.
In operating the liquid-tank combined condenser thus constructed (or the vapor compressing type refrigerator having such a condenser incorporated thereinto), the refrigerant flows in the direction of arrows, and is condensed and liquidized in the condenser 2 and then is fed to the liquid tank 3. The water content, foreign material and the like are removed from the refrigerant in the liquid tank 3, and the refrigerant thus made clean is discharged through the outlet pipe 22 into the expansion valve 4 located in the prestage of the evaporator 5 (see FIG. 23). The liquid-tank condenser thus constructed and operated is advantageous in that the condenser 2 and the liquid tank 3 may be handled as one body. Accordingly, it may readily be installed in a limited space within an engine room. One vibration-proof measure suffices for both the condenser 2 and the liquid tank 3. In other words, there is no need of taking the vibration-proof measures for the condenser and the tank, respectively. In this respect, the installing work of the condenser is easy.
In the conventional liquid-tank combined condenser structure (first example) shown in FIG. 24, the case 14 is directly mounted on the outer surface of the heater pipe 6a. Other conventional liquid-tank combined condenser structures are disclosed in the publication (Japanese Patent Publication 10. Hei. 4-103973). In the condenser structures, the case 14 is indirectly mounted on the outer surface of the header pipe 6a, as shown in FIGS. 25 to 28. In the condenser structure (second example) shown in FIGS. 25 and 26, the case 14 is mounted on the outer surface of the header pipe 6a in a state that a heat insulating member 23 is located between them. In the condenser structure (third example) shown in FIGS. 27 and 28, the case 14 is mounted on the header pipe 6a by means of a couple of upper and lower brackets 24.
Those conventional liquid-tank combine condenser structures have the following problems.
In the first example of FIG. 24, the case 14 of the liquid tank 3 must be hard soldered onto the header pipe 6a of the condenser 2 over the entire length of the contact area between them. Accordingly, heat of the header pipe 6a is directly transferred to the case 14. As a result, temperature of the liquid refrigerant contained in the liquid tank 3 rises, and the performances of the vapor compressing type refrigerator are degraded.
In the example of FIGS. 25 and 26, bonding work is essential, which is for bonding the outer side of the header pipe 6a to one side of the heat insulating member 23 and the inner side of the case 14 to the other side of the heat insulating member 23. Use of only the hard soldering work of aluminum material is insufficient for manufacturing the liquid-tank combined condenser structure. Accordingly, the manufacturing work is complicated and the cost to manufacture is increased.
In the third example of FIGS. 27 and 28, a gap 25 is present between the outer surface of the header pipe 6a and the inner surface of the case 14. Air flows through the gap 25. This air flow acts to decrease the efficiency of the condenser 2. Specifically, in operation, air flows through the spaces defined by the flat heat transferring pipes 7 and the fins 8 (see FIG. 24, but not illustrated in FIGS. 27 and 28). The refrigerant flowing through the flat heat transferring pipes 7 is condensed by the air. When the air flows through the gap 25, the air flowing through the spaces defined by the flat heat transferring pipes 7 and the fins 8, is reduced. The (operating) efficiency of the condenser 2 is reduced.
Furthermore, the conventional liquid-tank combined condenser thus constructed and operated is disadvantageous in that it is impossible to detach the liquid tank 3 from the condenser when the liquid tank 3 is repaired or replaced with another. In other words, when the liquid tank 3 is abnormal and it must be removed for finding its cause and repair the tank, the condenser 2 must be removed together with the tank. This makes the maintenance work of the liquid tank 3 difficult, and increases the maintenance cost. The same thing is correspondingly applied to the invention disclosed in Japanese Patent Publication No. Hei. 3-87572.
Such a structure that the liquid tank is detachable from the condenser is disclosed in Japanese Patent Publication No. Hei. 4-131667. In the structure disclosed, the header pipe is coupled with the liquid tank by fixing them at two locations, i.e., the upper and lower locations. Accordingly, the coupling work is troublesome, and the assembling work, repairing and part replacing work are also troublesome. The result is increase of the cost to manufacture.